Magnetic alloy



Patented May 23, 1933 UNITED STATES: PATENT OFFICE,

WILLOUGHBY STATHAM SMITH, OI BENCHAMS, NEWTON POPPLEFORD, HENRY JOSEPH GARNETT OF LYMNE, SOLEFIELDS, SEVENOAKS, AN'D WALTER FREDERICK RANDALL, OF EWELL, ENGLAND, ASSIGNORS TO TELEGRAPH CONSTRUCTION AND MAINTENANCE COMPANY, LIMITED, OF LONDON, ENGLAND, AND DEUTSCH-.' ATLANTLSCHE TEIEGRAPHEN'GIBELLSOEAFT, OF BERLIN, GERMANY MAGNETIC ALLOY li'o Drawing. Application filed July 11, 1932, Serial No. 622,012, and in Great Britain July 22, 1931.

mixed crystals with the nickel-iron complex brought into solution at a high temperature,

kept ,in supersaturated solution by rapid cooling and separated in a very finely d1- vided state by prolonged heating at a comparatively low temperature. The coercive force of the nickel-iron alloy is thereby increased and the'permeability curve in the.

range of small field strengths flattened.

- For the continuous loadingof signalling conductors, particularly in submarine telephone cables, it is desirable that the magnetic material should not only exhibit as constant a permeability as possible under the conditions prevailing in the immediate neighbourhood of the conductor during signalling, as well as low hysteresis losses, but it should also have a high specific resistance in order to diminish the eddy current losses occurring in the magnetic material during signal ling. Further the mechanical properties of w the metal must be such that it can bebrought into the form of thin tape or fine wire.

The present invention aims to produce workable magnetic alloys having not .only a high degree of constancy of permeability in weak magnetic fields, but also a high specific resistance.

According to theinvention there is incorporated into the alloy a resistance-increasing element which passes into solid solutionin the nickel-iron complex as well as the'sma'll percentage of theslightly-sol- .uble. constituent which latter, or some of it, when the alloy is annealed at a hightemperature, cooled rapidly from the annealing temperature or from an intermediate temperature, and then soaked'at a'comparatively .low temperature for asubstantial period of time,

is precipitated out of solid solution in a finely divided state. I

The term a resistance-increasing element used 1n this specification and the appended claims is intended to include one or more ele- -u ments of the group, known to have the property of increasing the resistance of nlckel- 11'011 magnetic alloys, which comprises, chronnum, molybdenum, tungsten, manga nese, copper, aluminium, silicon, vanadium,

cobalt. I

It is not posible to state precise limits for the proportionsof chromium, etc. to be incorporated because these would vary according to the extent of solid solubility in the particular nickel-iron complex employed, As a general guide the upper limits may be stated to be, for chromium (15%), molybdenmn (12%), manganese (12%), tungsten (10%), copper (15%), aluminium (5%), sil-" (5%), vanadium (5%), and cobalt (15%)..

It must further be understood that the nature and amount of the above mentioned soluble constituents will govern the optimum amount, and in some cases the choice, of the slightly soluble constituent to be added for producing the best working properties.

Examples of a suitable slightly soluble element are silver, beryllium, antimony,- magnesium, calcium, phosphorous, sulphur, carbon. It is to be understood thatan alloy produced according to the invention may in; corporate one or more of these elements.

It is of advantage in some cases to anneal? at a higher temperaturethan 900 C., for example at 1,000 C. or slightly above, since the absolutevalue of the permeability in its range of substantial constancy can thereby be raised. The rapid-cooling may be im-" present 1n the nature of accidental impuri-- ties.- The proportion of certain elements, I

notably sulphur, hosphorus and zirconium, required to pro uce, after the heat-treatment, the desired-flattening of the p/H curve in the range of small field strengths is'quite small; further the presence of certain elements, such as sulphur or phosphorus, in excess of a certain small proportion dependent upon the composition of the alloy leads to the production of brittle alloys. in e2;- ceptional cases it may happen that impurities of the desired kind are present in excess of the desired am0unt0r alternatively the impurity may have a deleterious effect on the further constituents that it is desired to add-and there may then have to be applied a purifying treatment to bring about the necessary adjustment (including, it may be, the elimination or reduction of unwanted constituents) before carrying out the annealing, quenching and soaking.

' The inventionv is illustrated by the following table of examples (the rows 1(a),

i 2(a), etc. being inserted for comparison purposes) u gimme Ooefllcl ent g reslst- Initial :gg x gev dighi 3 abllit y tion -m m on) (H -i2) percm') o Annealed (1 46.0 4660 0.0666

honr)at1w) 0., slow] cooled (i houm)to600 0. endthen repidlycooled.

' Seine 4:)!01- 47.0 am 0.0150

wed Y home I 375C A" NiekeL...----: 1,.2 Annealed (1 40.: mo c1000 Bemeas a)lolm use amour:

lowed 7 36 home et3750 be c) (o I Niekd 78.5 Annealed (1 50.5 m 0.0101

Inn. 18.0 hour) at 1000' Molybdenum 0., gleiwl Manganese-u coo e Bmeon--.----

gung meom Mum--- y then I Semeefle) m 51.!) an 0.0000

lowed by 5 houl'laoekin: nm'o 'a substantial period of time in order to ability variation, which *the incorporation into s0l 1d solutionin the for example as'600, G, quenchin so as to What we claim is p 1. The process of producing magnetic alloys of tlieni'ckel-iron class suitable for use i in loading signalling conductors being workable to shape as desired and having high specific resistance and low coefficient of permeability variation, which process comprises the incorporation into solid solution in the alloy of a resistance-increasing element and also the incorporation of a small percentage of a slightly soluble element, .,heating the alloy and quenching it from a high temperature so as to obtain a condition of supersaturation of the slightly soluble element in solid solution and thereafter soaking the so material at a lower temperature for a substantial period of time in order to precipitate some of that element out of solution in a finely divided state.

2. The process of producing magnetic alloys of the nickel-iron class suitablefor use inloading signalling conductors being workable to shape as desired and having high specific resistance and low coeflicient of permeability variation, which process comprlses the incorporation into solid solution in the alloy of a resistance-increasing element and also the incorporation of a small percentage of a slightly soluble element, heating the alloy to an annealing temperature, quenching so as to obtaina condition of supersatu ration of the slightly soluble element in solid solution, and thereafter soaking the material between about 300 and 500C. for

precipitate some of that element --out of solution in a finely divided "state. v A

3. The process of producing magnetic alloysof the nickel-iron class suitable for use in loadin signalling conductors being work- 6 able to s ape as desiredvand having high specific resistance low' coefiicient of permerocess comprisesv alloy of a resistance-increasing element and also-the incorporation of a small percentage of a slightly soluble element, heating the alloy to an annealing temperature, coolin rather slowly to a lower temperature, suc

obtain a condition of supersaturation of the sli htly soluble element in solidsolution,

an thereafter soaking .the material between about 300 and 500 C. for a substantial perlod of time inorder to precipitate some of that element out of solution in a finely divided state.

A magnetic alloy of the nickeleiron class which is non-brittle and suitable. for

use in loading conductors, hav- 125, c

ing a high spec resistance and an ade-' quately 'gh initial permeability coupled with a low' coeflicient of permeability varia-' tion and which contains a resistance-increasing element in solid solution and a small percentage of a slightly-soluble element out of solid solution and dlsseminated in a fine- 1y divided state throughout the mass of the alloy. 5. A magnetic alloy as claimed in claim 4, silver being speclfied as the slightlysoluble element.

6. A magnetic alloy as claimed in claim 4, beryllium being specified as the slightlysoluble'element;

In testimony that we claim the foregoing as our invention we have signed our.\.4mes this 30th day of June 1932.

WILLOUGHBY STATHAM SMITH. HENRY JOSEPH GARNETT.

WALTER FREDERICK RANDALL. 

